Sometimes sequels can be great things. They can develop a character, expand a world, explore new ideas, deliver new thrills, and make a healthy profit for the movie industry - all built upon the foundation of an earlier film. The Bourne franchise has had its fair share of this; The Bourne Identity was a well paced, well executed spy thriller that broke a dry spell of good spy thrillers (just have a look at the Bond movies coming out then). The Bourne Supremacy took the idea further - introduced new well-integrated characters, better explored Jason Bourne's motivations, and dialled up the action to boot. The Bourne Ultimatum improved on everything in Supremacy, and tied things up nicely with a happy - and importantly, non-violent ending.
The Bourne Legacy takes that fantastic foundation, chucks it in the dumpster, and goes on to tell its own mediocre story that taints the beauty of the first three films.
